package com.cuit.utils;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;

/**
 * @author cfy
 * @date 2022/12/2 0:09
 * @desciption: 下载工具类
 */
@Slf4j
@Component
public class DownloadFile {

    public void download(FileUtils fileUtils, HttpServletResponse response){
        String fileUrl = fileUtils.getFileUrl();
        // 获取文件名
        String filename = fileUtils.getFileName();
        try {
            // path是指想要下载的文件的路径
            File file = new File(fileUrl);
            log.info(file.getPath());
            // 获取文件名
            // 获取文件后缀名
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toLowerCase();
            log.info("文件后缀名：" + ext);

            // 将文件写入输入流
            FileInputStream fileInputStream = new FileInputStream(file);
            InputStream fis = new BufferedInputStream(fileInputStream);
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();

//            // 清空response
//            // JSONP 解决跨域问题
//            response.reset();
//            response.addHeader("Access-Control-Allow-Origin", "*");
//            response.addHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
//            response.addHeader("Access-Control-Allow-Headers", "Content-Type");
//            // 设置response的Header
//            response.setHeader("Content-Disposition", "attachment;filename="
//                    + new String(filename.getBytes(),"UTF-8"));
//            response.addHeader("Content-Length", "" + file.length());
//            OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
//            response.setContentType("application/octet-stream");
            // 清空response
            response.reset();
            // 设置response的Header
            response.setCharacterEncoding("UTF-8");
            //Content-Disposition的作用：告知浏览器以何种方式显示响应返回的文件，用浏览器打开还是以附件的形式下载到本地保存
            //attachment表示以附件方式下载   inline表示在线打开   "Content-Disposition: inline; filename=文件名.mp3"
            // filename表示文件的默认名称，因为网络传输只支持URL编码的相关支付，因此需要将文件名URL编码后进行传输,前端收到后需要反编码才能获取到真正的名称
            response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
            // 告知浏览器文件的大小
            response.addHeader("Content-Length", "" + file.length());
            OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            outputStream.write(buffer);
            outputStream.flush();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}
